Eutrophication in the Great Lakes, especially Lake Erie, has caused the creation of regulations limiting the phosphorus that may be discharged by wastewater treatment plants to 1 mg P/L. Municipal plants in Ohio have made significant improvements in their ability to remove wastewater phosphorus during treatment. During 1980, the flow-weighted average concentration of phosphorus in wastewater discharges for the Ohio Great Lakes Basin was 1.57 mg P/L, based on data from the Ohio Environmental Protection Agency (OEPA). When 11 more plants reach the goal of the regulations, the average will drop to 1.0 mg P/L. Achievement of this goal will make wastewater discharges a minor contribution (about 6%) of the total phosphorus entering Lake Erie.